This happens all the time. Most likely there are schedule changes on some of your flights. Could be very minor change like leaving 5 minutes early.

As soon as such change occurs (at least for partner flights), they ADD a new flight with the new schedule to your itinerary. At one point my 9-segment reward had 18 segments shown when viewed on aircanada.com . This becomes "invalid" under aeroplan.com

Every once in a while they clean it up and it will display properly on aeroplan.com .

If you don't mind calling+waiting, you can call up aeroplan to have them correct it right away.